Rising CO2 from historical concentrations enhances the physiological performance of Brassica napus seedlings under optimal water supply but not under reduced water availability.

The productivity of many important crops is significantly threatened by water shortage, and the elevated atmospheric CO2 can significantly interact with physiological processes and crop responses to drought. We examined the effects of three different CO2 concentrations (historical ~300 ppm, ambient ~400 ppm and elevated ~700 ppm) on physiological traits of oilseed rape (Brassica napus L.) seedlings subjected to well-watered and reduced water availability. Our data show (1) that, as expected, increasing CO2 level positively modulates leaf photosynthetic traits, leaf water-use efficiency and growth under non-stressed conditions, although a pronounced acclimation of photosynthesis to elevated CO2 occurred; (2) that the predicted elevated CO2 concentration does not reduce total evapotranspiration under drought when compared with present (400 ppm) and historical (300 ppm) concentrations because of a larger leaf area that does not buffer transpiration; and (3) that accordingly, the physiological traits analysed decreased similarly under stress for all CO2 concentrations. Our data support the hypothesis that increasing CO2 concentrations may not significantly counteract the negative effect of increasing drought intensity on Brassica napus performance.

Quantifying the impact of exogenous abscisic acid and gibberellins on pre-maturity α-amylase formation in developing wheat grains.

To study the role of abscisic acid (ABA) and gibberellins (GA) in pre-maturity α-amylase (PMA) formation in developing wheat grain, two glasshouse experiments were conducted under controlled conditions in the highly PMA-susceptible genotype Rialto. The first, determined the relative efficacy of applying hormone solutions by injection into the peduncle compared to direct application to the intact grain. The second, examined the effects of each hormone, applied by either method, at mid-grain development on PMA in mature grains. In the first experiment, tritiated ABA ((3)H-ABA) and gibberellic acid ((3)H-GA3) were diluted with unlabelled ABA (100 µM) and GA3 (50 µM), respectively, and applied at mid-grain development using both methods. Spikes were harvested after 24, 48 and 72 h from application, and hormone taken up by grains was determined. After 72 h, the uptake per grain in terms of hormones applied was approximately 13% for ABA and 8% for GA3 when applied onto the grains, and approximately 17% for ABA and 5% for GA3 when applied by injection. In the second experiment, applied ABA reduced, whereas applied GA3 increased α-amylase activity. This confirmed that exogenously applied ABA and GA were absorbed in sufficient amounts to alter grain metabolism and impact on PMA.

Effect of environment and variety on the relationships of wheat grain physical and chemical characteristics with ethanol yield.

BACKGROUND: Following the Renewable Transport Fuel Obligation (RTFO), there is an increasing demand for wheat grain for liquid biofuel in the UK. In order to enhance productivity of the bioethanol industry, good quality wheat must be used. RESULTS: A total of 84 grain samples comprising 14 varieties collected from 11 sites in two harvest years were analysed for a range of grain quality parameters and ethanol yield (EY). The grain quality parameters studied were starch and protein concentration, specific weight, grain density, packing efficiency, thousand-grain weight (TGW), grain length, width, length/width ratio and hardness index. Regression analysis was used to establish the relationships between grain quality parameters and EY. Apart from grain length and density, all grain parameters had significant relationships with EY. In the order of importance, protein concentration, TGW, packing efficiency and specific weight showed good relationships with EY. All other parameters, including starch concentration, showed a poor correlation with EY. EY and the relationship with the grain parameters were affected more by environment than by variety. Some sites gave consistently higher EY than others. When site and variety were considered with TGW and protein, a good prediction of EY could be made (variance accounted for = 87%). CONCLUSION: Combining TGW and protein concentration could be a better indicator of EY than the current practice of specific weight and protein.

Relationships between disease control, green leaf duration, grain quality and the production of alcohol from winter wheat.

BACKGROUND: Since demand for distilling wheat is expected to increase rapidly as a result of the development of the bioethanol industry, efficient production will become of increasing importance. Achieving this will require an understanding of the agronomic factors that influence both grain yield and alcohol yield. Therefore five field experiments using the winter distilling wheat variety Glasgow were conducted over three seasons (2006-2007, 2007-2008 and 2008-2009) to study the relationships between foliar disease and alcohol yield. RESULTS: There was a significant relationship between alcohol yield and the severity of the disease septoria leaf blotch (Septoria tritici), which was present in the experiments from natural infection. Retention of green flag leaf area as affected by disease control following fungicide application was also shown to be important for achieving high alcohol yields. Measurements of grain quality showed that high thousand-grain weight and low grain protein concentration were significantly related to increased alcohol yield. CONCLUSION: The experiments showed the importance of disease management to protect alcohol yields in the distilling wheat crop. Fungicides that provide greater disease control and improved green leaf retention are likely to be beneficial to alcohol yield.